Kofi Annan, the first black African to become UN secretary-general, has died aged 80 in Switzerland, his aides say.
He “passed away peacefully on Saturday after a short illness”, the foundation named after him said on Saturday.
Mr Annan served two terms as UN chief from 1997 to 2006, and was awarded a Nobel Peace Prize for humanitarian work for his efforts.
He later served as the UN special envoy for Syria, leading efforts to find a peaceful solution to the conflict.
In a statement announcing his death, the Kofi Annan Foundation described him as a “global statesman and deeply committed internationalist who fought throughout his life for a fairer and more peaceful world”.
“Wherever there was suffering or need, he reached out and touched many people with his deep compassion and empathy. He selflessly placed others first, radiating genuine kindness, warmth and brilliance in all he did.”
The career diplomat, who was originally from Ghana, died in hospital in the Swiss city of Bern. He had been living near Geneva for several years before his death.
He was awarded the Nobel Peace Prize in 2001 for helping to revitalise the international body, during a period that coincided with the Iraq War and the HIV/Aids pandemic.